Three people died, while another four were taken to hospital as a result of an incident in the South Side area of Pittsburgh, Pennsylvania on Sunday, according to Pittsburgh police.
The police reported that the authorities are responding to a "medical situation" at the scene.
Police officers reported that the situation took place at a block of flats at the South Side Works on Tunnel Boulevard. Five people were found in a flat, one person in a lift and another on the street. The condition of those taken to hospital varies from serious to critical.
Police said a preliminary investigation found no signs of any drug-related paraphernalia.
The victims are said to have worn orange wristbands. The probe identified at least two venues where such wristbands could have been used.